Knowledge Base

Decrements the HH register.

The behaviour depends on whether the last RTCRead was a time/event read or the date. If it was a time or event, the register decrements up to 0 then rolls under to 23. If the last read was the date, it decrements to 0 then rolls under to 99.

RTC documentation and tutorial

Dialect exclusions: Not available in dialects before 16.